I have tried unsuccessfully to perform string encryption. My grasp of the C language is not good. I have tried existing libraries without success, such as skipjack from avr-crypto, and also AES from another source.

If anybody was able to provide some assistance, I would be much appreciative!

if there was example code for XOR one time pad that would be fantastic!

The code I have been working with is as below. It only works for N_BLOCK chars which is 16. Any chars after that are ignored and don't get encrypted. I've tried to use multi-dimentional byte arrays and its getting ugly